Best available copv



Nov. 6 1923.

E. A. BOHLMAN KEY Filed Oct. 11, 1920 2 Sheets-Sheet 1 Nov. 6 1923. 1,472,787

E. A. BOHLMAN KEY Filed Oct. 11. 1920 2 Sheets-Sheet 2 j Eff m zzifiiz" iii/72522 Patented Nov. 6, 1923.

UNITED STATES PATENT OFFICE.

ERNEST A. BOHLMAN, OF CHICAGO, ILLINOIS. ASSIGNOR TO KELLOGG SWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

KEY.

Application flied October 11, 1920.

."0 all whom it may crmcem:

Be it known that I, ERNEST A. BOIILMAN, a citizen of the United States, and residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Keys, of which the following is a description.

My invention relates to an operating key for selective party-line ringing and has to do more particularly with that class of keys wherein the last key. depressed remains in a partly depressed or indicatingpositionby reason of its engagement with a mechanical latching device to indicate to the operator which key was last operated. I

An ob ect of my invention is to provide an improved form of construction so as to insure the efficient operation of the key, and to provide a structure of few and simple parts, easily assembled and easily accessible.

A feature of my invention 15 the provision of an improved plunger: rod constructed without expensive machining operations, which provides convenient mountings ace for the spring operating roller, anda constructed as to prevent it from rotating in.its guideswithout the use of extralpartssfor this purpose.

Another feature of my invention is the means provided whereby the springs associated with, thesprin operatln plunger are assembled units an convenient y secured to a mounting. plate so that if a spring unit of a particular key lun r is'in need of repair or a different com ination is desired. it may be replaced Without disturbing any of the other spring units.

A further feature of my invention is the novel construction of the latching plate in combination with the key plungers, which brings about a positive latchin and unlatchin of the key-plungers an maintains the di erent actuating members of the key in their various positions.

In well-known party-line ringing keys, a plurality of reciprocating keys and a rocking two-way key are provided, the reciproeating keys being used for ringing purposes and the two-way. rocking key for listeningand ringing purposes. Keys of the above type are constructed to indicate which one of the key plungers was last operated, but no indication is given when the rocking Serial No. 416,184.

key was last actuated for ringing purposes. Another feature of my invention therefore, is the provision of an arm associated with the rocking key which is operatively associated with the latching plate in such a way that when the rocking key is actuated for ringing purposes the latch plate is actuated so as to release any ottnormal key plunger to thus indicate to the operator that the rocking key was the last one operated.

My invention also includes other features and details which. together with the above, will be more fully understood upon reference to the following detailed description taken in connection with the accompanying drawings, in which like reference characters in the several views denote like parts, and in which Fig. 1 is a side elevation of the key structure of my invention;

Fig. 2 is a plan view of Fig. 1;

Fig. 3 is a righbend view OFFig. 1

Fig. 4 is areverse side elevation of Fig. 1;

Fig. 5 is a right-end view of Fig. 4:;

Fig. 6 is a bottom view of Fig. 4;

Fig. 7 is a sectional view along the line 77 of Fig. 1, showing the key plunger in its normal inoperated position; Fig-8 is a view similar to Fig. 7, but. showing the key plunger in its fully depressed position;

Fig. '9 is a view similar to Fig. 7, but showing the key plunger in its locking or indicating position;

Fig. 10 is a partial side elevationof the key showing the two-way mocking key. in its listening position; i

Fig. ll is a view similar to Fig. 10, but showing the two-way rocking key in its rmgn'lg position;

Fig. 12 is a sectional view along the line 12-42 of Fig. 1, showing the two-way rocking key in its normal position;

Fig. 13 is a sectional view along the line 13-13 of Fig. 11. showing the two-way rocking key in its ringing position and illustratin; the arm associated with the rocking key, having moved the latching plate to the left to allow the restoration of a key planner that is in indicating position;

Fig. l-l is an end view of the key with parts broken away to illustrate the position of the latch plate when a key plunger is in its fully depressed position, and its cooperating button which operates the end springsiofrthe key;

Fig. 15 is a perspective view of the latch plate; and

Fig. 16. is a perspective. view of the key plunger.

The combined key construction includes a plurality of ringing keys of the plunger type in association with a ringing and listening key of the leveror rocking type, all mounted compactly upon a frame. Each longitudinahmovable keyhas three operatingkpositions, a normal, 'a fully depressed an an intermediate position, the fully de pressed position being the position in which the end springs commontothe key plungers are actuated and the intermediate position being the ringing position and indicating position. A piirotedlatrhor catch plate cooperateswith the key plungers in retaining them in their various operating positions. The rocking key cooperates with the latch plate to restore any operators key plunger whenithe rockip key is actuated to its ringing position.

Referring now in detail to my invention as illustrated i'n t he accompanying drawings, it comprises an escutcheon plate 2, and secured thereto by means ofjhe screwsGO is an inverted U-shaped frame 3, upon which are mounted the operating parts of the key. The lower ends 4 and of the inverted -U-sl 1ape d' franie 3 are connected by the springsupportjng plate ,6, which is secured to the ends 4 and 5 of the frame 3 by means of the screws 7, and a plunger gnidingfplate 8 is secured to the ends 4.an'd5 by meaps of screws 9. The spring su porting plate 6 has secured to it a plura ity of U-shaped mem,bers 10 by means ofscrews 11, and insulatingly mounted upon the members 10 are the sprin contact members 12. 13Yand 1.4. I have il ustrated four key plungers, this being the usual number in the party-line key, and as the key plungers areall similar in construction, a description of one will sullice for a clear understariding of thekey.

As shown in the drawing, the plunger rod P is made of a metal stamping and comprises an upper portion 15. an intermediate or body portion 1 and a lower portion 17. The upper portion 15 extends upward through suitable openings 18 and 19 in the plate 2 and frame 3, and the lower portion 17 enters a guide hole in the angular portion 21 of the connectingplate S. The plungeinrod is made preferably flat. and the upper and lowerportions i5 and 17 are rectangular in shape and pass through suitable rectangular orifices 18 and 19 in the plate 2 and frame 3, and a rectangular orifice 20 in the angular portion 21 of the connecting plate 8. to prevent the turning of the key plunger. An anti-friction roller 22 is rotatably secured to the outer face of the body portion 16 of the plunger IOtl by means of a pivot screw 23 and is adapted to engage the spring 13 (0 move it from engagement with the spring 14 and press it into engagement with the springlz. The plunger rod is also provided with a projection 24 integrally formed with the body portion 16 of the plunger rod P by means of a shearing operation and adapted to cooperate with the latch plate 25 for purposes as will he presently described.

Referring now to the latchplate 25 as clearly illustrated in Fig. 15 it is prefer,- ably stamped from a single sheetof-metal and is secured to the legs 4 and fi of the shaped frame 3, andfor this purpose the latch plate 25- is provided'on its opposite ends, adjacent to its lower edge," with pro; ecting members or' ears 26 and-2L7 adapted to lie fiat againstthe inner faces of the legs 4 andv5, and ,is piyotally secured thereto by means of the'piv'ot pinsj28; Allongfthe up-,

per edge, 29 of the latch plate 25 I provide'a pluralityof angular projecting members 30 integrally formed witlrthe' said latch plate 25 and which members 30 are adaptedto engage the projections or. tongues 24, of the plunger rods I pressed to hold .the said key in' its indicating pos tion.

The. latch plate 25 is rpyided with rearwardly projecting mem is or tongues 31 which are formed, integrally therewith by means of asbearing operation- Now, when a key plunger P is fully depressed, the tongue 24 on the plunger rod 'P-ngages the tongue 31 of'thelatcli' plate 25 and moves the said latch plate' 25,outwar( lly to unlatch any key plunger l 'that may be in its indicating position, as will more fully hereinafterdescribed, Near its upper edge and at one end of'the plate 25, I proi idean integrally formed arm 32 extendingat right angles to the faeetof 'the plate 25. 'i*\ laberally projecting member-33 of suitable insulating material is' secured to the arm 32 of the pla te 25 by meansof a scrcw 34 and is arranged to project through ,a slotted-openin 35 inthe leg 4 of the frame 3, and is ac apted to engage.a spring36 of the end springgroup ESto move the end springs to their alternate positions when a keyjplnnger is depressed to its fully depressed position, as will be more fully hereinafter described.

The end spring group ES comprises springs 36, 37, 38, 39, 40 and 41-. which are suitably mounted upon an angular bracket 42. which bracket 42 is secured to the leg 4 of the frame 3 bymeans of the screws 43. The springs 36, 37,. 38, ctc.. are insulatinglv secured to thevbracket 42by means of the screws 4-4.

As previously indicated, the key structure includes a listening key lever L, which extends through a suitable opening in the P when one.of themi-is de i 'g s. Pas ies oscu'tcheon 2. The key comprises a T- shaped frame 45 which is suitably fastened to the escutcheon plate 2 by means of screws 46. A semi-circularly shaped actuating 5 member 47 for actuatin the contact springs comprises a pivoted yor cam and pivotally supported in the frame 45 by means of the pivot pin 48. Mounted upon the lower end of the cam 47 are rollers 49 and 50 of suitable insulating material, and rotatably secured thereto and positioned between the free ends of the pair of sprin s 51 and 51 of the listening spring group L and the free ends of the pair of springs 52 and 52 of the ringing spring figoupdlttsil The lisan I e ringing tening spring roup spring group S are insulatingly mounted upon the frame 45 by means of insulated screws 53.

In keys of the above type in which a two way rocking key is provided in addition to the usual four-party ringin keys, indicat ing means are adapted to indicate which one of .the 'key plungers was last operated,

hut no indication is given when the in th'eposition asclearly illustrated in Figs.

1 and13, The latch plate 25 is provided on the side opposite thatof the projection 32 with a downwardly extending ear 56 angularly displaced inwardly relative to the face of the 'latch plate 25, and, this ear 56 is operatively associatedjwith' the nose 57 of the annj54; andfengageflhyfihe saidf nose 57 to movethe p'lat'flfii outwargi when the lever L d ftlie"ljreyi is moved to the left plunger that may in a n indicating positionj .as will'be more; fully hereinafter described.'"',The"latcli plate 25' is held in its position means of a coilspring'58,'which spring'58 has one of its'endssecured to the 1) ate 25 and its other end secured to a ,pin 59, which pin 59' is suitahlysecur'ed to the leg 4 of the fraine 3.

In' th" toperatio n'of ariy one of a the keys the movement of the parts F lows: Assuming'tliat the key' starts from its normal position, the first movement thereof will hring the cam surface 61of the angular projection 24 of the key plunger .13 intoengagement with the edge 62 of the member 30 of the latch plate 25, and the continued downward movement of the key plunger" P forces the said latch plate 25 outwardly a inst the action of the spring The'rol er 22. secured to the body 'por tion 16 of the plunger P, when moved into engagement with the spring 13, forces it out'of engagement with a spring 14 and into engagement with the spring 12. The

G5 downward pressure on the key plunger rod 0 milatch any key is continued to force the said key plunger into its fully depressed position. After the apex 63 of the projection 24 of the key plunger passes the edge 64 of the member 50, the cam face 61 of the projection 24 now engages the face 165 of the inwardly projecting member 31 of the latch plate,25 and further forces the )late 25 outwardly until the plunger is in t e position as illustrated in Fig i. The movement of the plate 25 forces the member 33 secured to (he a rm 32 into engagement with the spring 36. moving the end springs 36, 37, 38, 39, 40 and a l to their alternate posit ons. A coiled actuating spring (35 is provided which surrounds the lower portion 17 of the key plunger I, hearing at its opposite ends against the shoulder 66 of the plunger 1 and the angular portion 2i of the plate member 20.

This coiled spring is compressed when the key plunger P is depressed, and when the pressure of the finger is released-lthe coil spring 65 moves the key plunger-upward until the apex 63 of the projection=24 of the plunger 1 engages the bottom face 68 of the member 30, thus holdingthe key plunger in its indicating position, as ill u s-, l

her 33 to disengage the spring 36 and allow the springs 36, 37, etc., to assume their, normal position. Thus, it may be seenthat each time that a key plunger P is depressed,,the

end spring group ES assumes its alternate position. ger P is depressed, the projection 24 of the Assuming that another: key plunsaid key plunger engages. the, member 30,

forcing the plate 25toutwardly, as alreadyndescribed, andwhen the face, 68, of the memher 30 passes the apex 63 of the projection 21 of the key plunger P that is in; indicat,

ing position, it is released and the coils ring 1 4 65 forces the key plunger P from its in icating position to its normal inoperative positiOn. 1 1:2 Assuming that a key plun er P is in its indicating position and the lever L of the rocking key is moved to the left to operate its ringing contacts. The movement of the lever L rotates the cam 47 and as the arm 54 is secured to the cam 47 the said arm-is moved in a downward direction, causing the nose 57 of the arm 54 to engage the angular face 70 of the ear 56 of the plate 25. ,The

continued movement of the lever L causes the arm 54 to force the plate 25 outwardly. causing the face 68 of the member 30 -t0 disengage the apex 63 of the rojectioii 24 oil' the key plunger P that is in indicating position This releases the locked key plungcr P that is in an indicating position, and the coil spring 65 restores the said key pluiiger to normal. When the key lever L is moved to the right into listening position,

the arm 54- is moved in an upward direction and does not affect the latch plate 25 or any key plunger that may be in an indicating position:

Key-caps-or'buttons 71 of hard rubber or other suitable material are provided and are secured to the portion 15 of'the key plunger 1 by-means'of screws 72 which pass through suitable openings in the caps 71 and have s; rew-threaded engagement with suitable tapped'openings in the upper portions 15 of the key plunger P. Circular disks 73 of felt are-slipped over the portions 15 of the key plungers P, and circular disks 74 of metal are placed between felt' disks 73 and the-shoulder 75 formed by the portion 15 and the body portion -16 of the said plungers, and these felt disks-73 and disks 74 act as cushions when any one of the plungers are restored to normal by the action of the spring 65.

In Fig. 1I have-shown theplunger X controlling adifferently constructed set of springs than thezother -plungers control. When'th plunger X is' operated to its indicatingos'itio'n, it doesnot affect its springs These s rings are not affected until the plunger 5 ismoved to its fully operated position,- at which time the common endsprings are'operated, as well as the-"sprin s Y.- Ihave shown the plunger X con'trd li rig"th'is mb difie'tlset' of 'springs 'c'e'rtaintypes of ringing circuits m 'ire suclra set of springs.

r 'rorfithegforegoing it will be apparent thabflmy device is so constructed that when a p l1i n*er Pis'bperated a previously depresse plunger will'bereleased. before the plunger being; depressed has moved far enough tti be latched in its indicating position,-and that when the plunger is fa rthe r deprssedltlie latch' platepis moved outward] "fffarther and the. common end springs are operated;

While I have illustratjedand described a particular key structure. and spring ar rangemenql do'not, wish to be limited to the'eiact form, as many changes and modificatibiis may be made, without departing froin* the scope .ofthe invention, and I 'aim to cover all such chan es and modifications as colne within the spirit and scope of the ap nddclakns.

Vhait I claim as new and desireto secure by United States Letters Patent, is:

1 A device of the character described includi-nga frame, a plurality of reciprocatingplungers supported by said frame, said plungers having a cross-section to pre ent their rotation. relativeto said frame, an in tegrally formed earfor each of said plungers, a latcli' plate pivotally supported by said'frame, and integrally formed ems for said latch plate for cooperating with the ears of said plungers in such a. manner that when one plunger is depressed, theear of' said plungerengagcs one of the ears of said latch plate to release any previously operatcd plunger to its normal position and the depressed plunger is held in an indicating position by the ear of'said ph'inger engag ing one ofthe other ears of said 'latch' plate.

A device of the character described including a frame, a plurality of reciprocating plungers supported by said frame, an integrally formed ear fol-"each of said plun'gers, said plungers haringa cross section to prevent their rotation? relative to said frame, a latch plate pivotally sup ported by said frame and integrally formed ears for said latch plate for cooperation'f with siid ears of said .ilunge'rs in such a manner that when one p linger is depressed the ear ofsaid plunger engages one of the ears of the said latch plate to release'any previously operated plunger to its normal position and the depressed plunger is' held in anindicating-position by the ear of 'sa'id plunger engaging one ofthe other "ears of said latch plate, and spring contacts con trolled by each of said plungers 3. A device of thecharacter d'escriljedin; eluding a frame, a flurality o f 'reciprocat ing plungers carried by. said fiame,' eacli of said plunger-s having a normal, an indicat-' iug and a fully operated position, said plungers having a cross-section such -as to prevent their rotation relative to the frame, an integrally formed ear for 'eaclrof said plungers, a latch platepivotally, supported by said switch frame, airs of integrally formed ears for said .late plate, each pair' of said ears co0perating,w1tli1tl-ie ears on said plungers, the ro'Jecting' ears onsaid latch plate cooperating with the projecting,

ears on said lungers in such a manner that when one anger 1s depressed fromi its,

normal to Its indicating position, the. ear

of said' plungcrengages an ear ofapairi on said latchlate which are associated with said depressed plunger so that any previously depressed plunger will be released -to its normal position, and springs operable bysaidlatch plate when the plunger is further depressed from its indicating to. its fully operated position.-

4. A device of the character described includinga frame, a plurality of one-piece reciprocating plungers carried by saidframe, each of said plungers having 0, normal, an indicating and a. fully operated position, said plungers having a cross-section such as to prevent their rotation'relative to the frame, an integrally formedear for each of said plungers, a latch plate pivotally supported by said switch frame, airs of integrally formed -ears for said .lhtch plate, each of said pairs of ears being associated with, a key plunger and cooperating with the ears on said plungers, thepairs of projecting ears on said latch plate cooperating with the projecting cars on said plungers in such a manner that when one lunger is depressed from its normal to its indicating position the ear of said depressed lunger engages an ear of a pair on said atch plate, which are associated with said depressed plunger so that any previously depressed plunger will be released to its normal position, and a projecting ear for said latch plate cooperating with said frame for limiting the movement of said latch plate in one direction.

5. A device of the character described including a frame, a plurality of reciprocating plungers carried by said frame, each of said plungers having a normal, an indicating and a fully operated position, said plungers having. a crosssection such as to prevent their rotation relative to the frame, an

integrally formed ear for each of said pluh gers, a latch plate pivotally supported by said switch frame, integrally formed ears for said latch plate for cooperation with the ears on said lungers, the projecting ears on said latch p ate cooperating with the projecting ears on said plungers in such a mannor that when one plunger is depressed from its normal to its indicating position any previously depressed plunger will b released to itsnormal position, a projecting ea-r'for said latch plate for limiting said latch plate in one direction to cooperate with said limiting ear mal position.

:6. A device of the character described inclu ding a supporting frame. a plurality of reciprocating plunge-rs supported by said frame, rectangular slots in said frame in which said plungers are mounted and held againstrotary movement relative to the mounting frame, a spring supporting plate secured to said frame independently and free from said plungers. and a removable unit consisting of a plurality of switch springs for each of said plungers attached to said spring supporting plate.

7. A device of the character described including a supporting frame, a plurality of reciprocating plungers supported by said frame, rectangular slots in said frame in which said plungers are mounted and held against rotary movement relative to the mounting frame, a spring supporting plate secured to said frame independently and free from said plungers, and a mounting member to which switch springs are attached forming a unitary structure for each of said plungers. said unitary structure being adapted to be attached to said spring supporting plate in such a manner that it may be readily removed and the entire the movement of direction, and a rocking key-associated with said reciprocating plungersand adapted when moved in one be attached to said spring supporting-plate in such a manner that it may be readily re moved and the entire sp ringco'mbination 1 controllable by "any plunger ch'anged without dismantling the 'springs ofi'a'set, and a pivoted latch plate supported byi-said frame and provided with' -pairs"- ofliintegrally formed cars, a pairof saidrears being associate'd with each plunger andcooperating with said plungers in such a'manner'that when-one-of said plurig'ers is'depressed, said one lunger will be held in its depress d position untilanother ohexoi said plungers is depressed whereby saidlpreviously depressed plunger will restore 'to'its normal position and-said other depressed r p'lungerwv ill be T held; in itssindicating Iposi'tion =by itslear :en-

gagingtheear of aapaia' associated with said pthewdeprssed plungerJi 9. A device of the character described in-- cluding a supporting Hamm d-plurality of reciprocating; plungerssupported' 'by said frame, each provided; withran 'integrally formed ear; rectangular slots in said frame in "which said plun'grs are mounted and held'against rotary movement relative to the mounting'framefaspring supporting plate secured to said frame, a mounting member to which switch springs are attached forming a unitary structure for each of said plungersfi said unitary structure being adapted to be attached to said spring supporting plate in such a manner that'it may be rea-dilv removed and the entire spring combination controllable by any plunger changed without dismantling the springs of a set. a pivoted latch plate supported by said frame and provided with pairs of integrally formed earsya pairof said ears being associated witli each' plunger and cooperating with said plungers-in such a manner that when oheof said plungers is dercsscd. said one plunger will be held in its depressed position until another one of said plungers is depressed whereby said previouslv depressed plunger will restore to its normal position and said other depressed plunger will be held in its indicating position by its ear engaging the ear of a pair associated with said other depressed plungel, and a projecting car for said latch plate which cooperates with said mounting frame to limit the movement of said latch plate in 'one direction.

10. A device of the character described including a supporting frame, a plurality of reciprocating plunge'rs supported by said frame, rectangular slots in said frame in which said plungers are mounted and held against rotary movement relative to the mounting frame, a spring supporting plate securedto said frame, a mounting member to which switch springs are attached forming a unitary structure for each of said plungers, said unitary structure being adapted to be attached to said spring supporting plate in such a manner that it may be readily removed 'and the entire spring combination controllable by any plunger changed without dismantling the springs of a set, a pivoted latch pl-ate supported by said frame cooperating with said plungers in such a mannerr'that when oneof said plungers is depressed any :previously depressed plunger will restore. to its normal position, a projecting ear for'said :latch plate which cooperates with said mounting frame to limit the movement of said latch plate in one direction, and a rocking key associated with :s'aid mounting frame and plungers in such a manner that when the rocking key is snowed in :one direction it cooperates with said limiting member in a manner to release any plunger that -is than ofl'-norma-l pos'itfion.

'11. Adevice of the character described inclndin' a frame, a plurality of recipro eating p angers-supported by said frame, each being provid with an integrally formed ear, sa-id plungers having a crosssecti'on to prevent their rotation relative to said frame, pairs of integrally formed ears for :said latch plate for cooperation with the ears of said plungers in such a manner that when one plunger is depressed the ear of said plunger engages one of the ears of a pair on said latch lplate emaciated with said plunger so that any previously operated plunger will be released to it's norm'al position and the depressed plunger held in an indicating position by the ear on said depressed plunger engaging the other ear of the pair associate with said depressed plunger, spring contacts controlled by each of said plungers, and springs supported by said frame ado ted to be operated each time a plunger is moved from its indicating to its fully operated position.

12. A device of the character described including a frame, a plurality of reciprocating plungers supported by said frame, said plungers having a crosssection to prc vent their rotation relative to said frame. ears for said plungers, integrally formed ears for said latch plate for cooperation with the ears of said plungers in such a manner that when one plunger is depressed any previously operated plunger will be released to its normal position and the depressed plunger held in an indicating position, spring contacts controlled by each of said plungeis, springs supported by said frame adapted to be operated each time a plunger is moved from its indicating to its fully operated position. and a rocking key associated with said device and cooperating therewith in such a manner that when the rocking key is operated a plunger is released.

13. A device of the character described including a frame, a plurality of recipro eating plungers carried by said frame, each of said plungers having a normal, an indicrrting and a fully operated position, said plungers having a cross-section such as to prevent their rotation relative to the frame, an integrally formed ear for each of said p'lungers, a latch plate pivotally supported by said switch frame, pairs of integrally formed ears for said lat'ch plate, a pair of said ears being associated with an ear on 'each said plunger and adapted for cooperation with the ears on said plungers, other projecting means for said latch plate, the

ro'j'ecting'ear's on said latch plate cooperatmg with the projecting ears on said plungers in such a manner that when one plung er is depressed from its normal to its indieating position the ear of said plunger engages one of the ears of a pair associated 'wi'th said depressed plunger so that Iany previously depressed plunger will be released to its normal position, and springs operable by said latch plate when the plunger is further depressed from its indicating to its fully operated position, the ear on said plunger cooperating with the projecting means on said plate in such a manner when the plunger is moved from its indieating to its fully depressed position that the latch plate is caused to move to operate a set of springs common to the device.

Signed by me at Chicago, in the county of Cook and State of Illinois, this 9th day of October, 1920.

ERNEST A. BOHLMAN. 

